1. Field of the Invention
The present invention relates generally to a multifrequency resonant antenna, and more particularly, to an antenna apparatus including a plurality of elements and to a radio communicating apparatus.
2. Description of the Related Art
Recently, communication using a plurality of frequencies such as GPS (Global Positioning System) communication and telephone communication is increasingly diversified in radio communicating apparatuses such as portable terminal apparatuses. When using a plurality of frequencies, if an independent antenna is disposed for each frequency band, proportion of antenna is increased in a radio communicating apparatus. Therefore, it is requested to use a single antenna apparatus in a plurality of frequency bands.
With regard to an antenna apparatus corresponding to a plurality of frequency bands, in an antenna apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2002-330025, a non-feed radiation electrode is disposed on each branch radiation electrode of a feed radiation electrode, which is split into two branch radiation electrodes, and the branch radiation electrode and the non-feed radiation electrode on one side and the branch radiation electrode and the non-feed radiation electrode on the other side are driven into multiple resonance in different frequency bands (abstract, FIG. 3, etc.).
Japanese Patent Application Laid-Open Publication No. H05-283926 discloses a dipole antenna that includes a non-feed element in a surface surrounded by a folding dipole element to realize band sharing characteristics for a plurality of frequency bands (abstract, FIG. 1, etc.).
Japanese Patent Application Laid-Open Publication No. 2003-037426 discloses a helical antenna operable in a plurality of frequency bands that includes two non-feed coil units among windings of an excitation coil unit and the non-feed coil units are electromagnetically coupled to the excitation coil unit and are fed from the excitation coil unit (abstract, FIG. 5, etc.).
Since the non-feed elements are connected to ground in the antenna apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 2002-330025, a ground terminal unit is needed; an occupied area is increased in the dipole antenna disclosed in Japanese Patent Application Laid-Open Publication No. H05-283926; and the helical antenna disclosed in Japanese Patent Application Laid-Open Publication No. 2003-037426 is a narrow-band antenna.
Although the multifrequency resonance can be achieved by branching an antenna element, in the case of a communicating apparatus that cannot ensure a sufficient space for disposing an antenna element when the antenna element is branched, it is disadvantageous that the multifrequency resonance cannot be achieved or that necessary antenna characteristics cannot be achieved.
In Japanese Patent Application Laid-Open Publication Nos. 2002-330025, H05-283926, and 2003-037426, such requirements and problems are not disclosed or indicated, and structure, etc., for solving the problems are not disclosed or indicated.